Laser machining device

ABSTRACT

A laser machining device according to the invention is provided with a laser oscillator for generating a laser beam, a main deflecting galvannometer mirror, an Fθ lens, and a sub-deflecting means arranged in an optical path between the laser oscillator and the main deflecting galvanometer mirror. A means for splitting a laser beam is provided, and the sub-deflecting means is inserted into the optical path of one of the split laser beams. At the same time, both the split laser beams are incident from the same main deflecting galvannometer mirror to the Fθ lens, and a numerical aperture in the optical system constituted by the main deflecting galvannometer mirror, the Fθ lens, and an object is set to be not more than 0.08.

TECHNICAL FIELD

The present invention relates to a laser machining device and, moreparticularly, to a laser machining device used in high-speed precisehole drilling or the like.

BACKGROUND ART

FIG. 9 is a general laser machining device for hole drilling. In FIG. 9,a laser machining device 101 has a laser oscillator 103 for generating alaser beam 102, a bend mirror 104 arranged to guide the laser beam 102emitted from the laser oscillator 103 in a desired direction byreflection, galvanometer scanners 106 a and 106 b respectively havinggalvanometer mirrors 105 a and 105 b serving as movable mirrorssequentially arranged along an optical path, an Fθ lens 108 forconverging the laser beam 102 the traveling direction of which iscontrolled by the galvanometer scanners 106 a and 106 b onto an object107, and an X-Y stage 109 driven on an X-Y plane and having an uppersurface on which the object 107 is fixed.

The operations of the respective components used when hole drilling isperformed by using such a laser machining device will be describedbelow.

The laser beam 102 having a pulse waveform oscillated depending on afrequency and an output value which are predetermined by the laseroscillator 103 is guided to the galvanometer scanners 106 a and 106 b bythe bend mirror 104. One of the galvanometer scanners 106 a and 106 b isrotated in a direction corresponding to the X direction of the X-Y stage109, and the other is rotated in a direction corresponding to the Ydirection. Therefore, the laser beam 102 can be scanned at an arbitraryposition within a limited area on the X-Y plane. The laser beam 102 isincident on the Fθ lens 108 at various angles. The laser beam 102 iscorrected such that the laser beam 102 is incident on the Fθ lens 108 bythe optical characteristics of the Fθ lens 108 perpendicularly to theX-Y stage 109.

In this manner, the laser beam 102 can be freely positioned by thegalvanometer scanners 106 a and 106 b with respect to any coordinates onthe X-Y plane within a limited area (to be referred to as a scan area)on the X-Y stage 109. The laser beam 102 is irradiated on the positionto machine the object 107.

Upon completion of the machining in the scan area, the X-Y stage 109moves to a position serving as a new scan area of the object 107 torepeat machining.

In particular, when the object 107 is a printed circuit board, and whenit is desired to perform machining for a relatively precise hole, anoptical system may be an image transfer optical system. FIG. 10 is aschematic diagram showing the positional relationships between theoptical components when an image transfer system is used. In FIG. 10,reference symbol a denotes a distance between an aperture 110 forsetting a beam spot diameter on the object 107 and the Fθ lens 108 onthe optical path, reference symbol b denotes a distance between the Fθlens 108 and the object 107 on the optical path, and reference symbol fdenotes a focal distance of the Fθ lens 108. The focal distance f of theFθ lens 108 is set to be equal to the distance between the Fθ lens 108and a center position 111 on the optical path between the twogalvanometer mirrors 105 a and 105 b.

In the image transfer optical system the above positional relationships,the effective radiuses of the galvanometer mirrors 105 a and 105 b arerepresented by gr. In this case, when the distance a is sufficientlylarger than the distance b, a numerical aperture NA in the opticalsystem of the Fθ lens 108 and the object 107 is expressed by equation(1):NA=gr/(b ² +gr ²)^(1/2)  (1)

When the wavelength of the laser beam is represented by λ, a beam spotdiameter d on the object is expressed by equation (2)

 d=0.82λ/NA  (2)

In addition, since the image transfer optical system is used, a, b, andf are set to have such a positional relationship that the relationsexpressed by equation (3) is established.1/a+1/b=1/f  (3)

Therefore, for example, in order to obtain a beam spot diameter d of 95μm by a laser having a wavelength λ of 9.3 μm, the numerical aperture NAmust be 0.08 according to equation (2). In this manner, according toequation (2), in order to decrease the beam spot diameter d to performprecise hole drilling, the numerical aperture NA must be large.

For this purpose, it is understood according to equation (1) that theeffective radius gr at which a laser beam from the galvanometer mirrorcan be reflected without deteriorating the quality of the laser beam ispreferably increased. For example, in order to achieve a beam spothaving a diameter at least smaller than the beam spot diameter d=95 μmby an optical system which satisfies f=100 mm and b=107 mm, b=107 mm issatisfied according to equation (3). For this reason, in order tosatisfy NA>0.08, it is understood according to equation (1) that gr>8.6mm is satisfied.

In order to improve the productivity of the laser machining device, thedrive speed of the galvanometer scanner must be high. For this reason,in general, it is said that to decrease a galvanometer mirror or todecrease the deviation angle of the galvanometer mirror is effective.

Japanese Unexamined Patent Publication No. 11-192571 discloses a lasermachining device which branches a laser beam with a branching means,guides respective laser beams to a machining position with scanningmeans, and converges the respective laser beam to perform machining.

In addition, Japanese Unexamined Patent Publication No. 11-314188discloses a laser machining device in which a laser beam is split by ahalf mirror, and split laser beams are guided to a plurality ofgalvanometer scanners and irradiated on a plurality of machining areasthrough Fθ lenses.

However, when a galvanometer mirror diameter is decreased, an effectiveradius gr decreases, and a numerical aperture NA decreases according toequation (1). As a result, a beam spot diameter d which satisfies therelation expressed equation (2) increases, and such a problem thatprecise hole drilling cannot be performed is posed.

In addition, when the deviation angle of the galvanometer mirror isreduced, respective scan area sizes become small. For this reason, thenumber of scan areas increases. In general, since a time required forpositioning by the galvanometer scanner 106 is considerably longer thana time required for positioning of the X-Y table, the number of scanareas increases. When the number of times of movement by the X-Y stageincreases, although the speeds in the respective scan areas increases,such a problem that the entire production rate is not improved is posed.

Furthermore, in the device disclosed in Japanese Unexamined PatentPublication No. 11-192571, in order to control and converge slit laserbeams, galvanometer scanners (galvanometer meters and galvanometermirrors) and Fθ lenses corresponding to the respective laser beams arerequired. For this reason, when a laser beam is split into two laserbeams, galvanometer scanners and Fθ lenses the numbers of which aretwice the numbers of galvanometer scanners and Fθ lenses of the lasermachining device shown in FIG. 9, and the problem of an increase in costis posed. In order to simultaneously machine two objects to obtain twicemachining speeds, an X-Y table the size of which is twice the size ofthe X-Y table of the laser machining device is required, and such aproblem that the machining device increases in size is posed.

Still furthermore, in Japanese Unexamined Patent Publication No.11-314188, respective split laser beams are guided to a plurality ofindependent galvanometer scanner systems and converged by Fθ lenses. Forthis reason, since a laser beam which is incident from the finalgalvanometer mirror onto the Fθ lens in the optical path is largelyobliquely incident, the influence of the aberration of the Fθ lensincreases, and such a problem that the laser beam cannot be easilyconverged in a small area.

DISCLOSURE OF INVENTION

The present invention has been solve the above problems, and an objectis to provide a laser machining device which suppresses an increase incost while improving productivity in precise machining and which is notincreased in size.

Therefore, the laser machining device has:

-   -   a first scanner for deflecting a traveling direction of a first        laser beam to an arbitrary direction with a mirror;    -   a second scanner for deflecting traveling directions of a second        laser beam and the first laser beam passing through the first        scanner to arbitrary directions with mirrors; and    -   a lens for converging the second laser beam and the first laser        beam passing through the second scanner.

In addition, the laser machining device has a configuration in which

-   -   the first laser beam and the second laser beam have different        polarization directions, and    -   a beam splitter which reflects one laser beam and transmits the        other laser beam is arranged in front of the second scanner such        that the laser beams from the beam splitter are propagated to        the second scanner.

The laser machining device further has:

-   -   an oscillator;    -   a diffractive optics for splitting a linearly polarized laser        beam oscillated from the oscillator into a first laser beam and        a second laser beam; and    -   a phase plate for changing the polarization direction of the        second laser beam.

The laser machining device still further has:

-   -   an oscillator; and    -   a spectral beam splitter for splitting a circularly polarized        laser beam oscillated from the oscillator into a first laser        beam and a second laser beam having different polarization        directions, respectively.

Furthermore, an aperture is formed in front of the diffractive optics,so that an image transfer optical system can be formed between theaperture and an object arranged behind the lens.

Still furthermore, an aperture is formed in front of the spectral beamsplitter, so that an image transfer optical system can be formed betweenthe beam splitter and an object arranged behind the lens.

Furthermore, a distance in which the first laser beam is propagated fromthe diffractive optics to the lens is made almost equal to

-   -   a distance in which the second laser beam is propagated from the        diffractive optics to the lens.

Still furthermore, a distance in which the first laser beam ispropagated from the spectral beam splitter to the lens is made almostequal to

-   -   a distance in which the second laser beam is propagated from the        spectral beam splitter to the lens.

Still furthermore, a numerical aperture calculated by a mirror diameterof the second scanner and a distance between the lens and the object isset to be not less than 0.08.

The laser machining device has:

-   -   a first scanner for deflecting a traveling direction of a first        laser beam to an arbitrary direction with a mirror;    -   a second scanner for deflecting traveling directions of a second        laser beam and the first laser beam passing through the first        scanner to arbitrary directions with mirrors;    -   a third scanner for deflecting a traveling direction of the        first laser beam passing through the first scanner to an        arbitrary direction with a mirror; and    -   a lens for converging the second laser beam passing through the        second scanner and the first laser beam passing through the        third scanner.

Furthermore, an aperture is formed in at least one of the travelingdirection of the first laser beam in front of the first scanner and thetraveling direction of the second laser beam in front of the secondscanner, so that an image transfer optical system can be formed betweenthe aperture and an object arranged behind the lens.

Still furthermore, a numerical aperture calculated by the mirrordiameter of the second scanner and the distance between the lens and theobject is set to be not less than 0.08.

The laser machining device has:

-   -   a first scanner for deflecting a traveling direction of a laser        beam to an arbitrary direction with a mirror;    -   a second scanner for deflecting a traveling direction of the        laser beam passing through the first scanner to an arbitrary        direction with a mirror; and    -   a lens for converging the laser beam passing through the second        scanner,    -   an angle at which the laser beam is deflected by the first        scanner being smaller than an angle at which the laser beam is        deflected by the second scanner.

Furthermore, an aperture is formed in front of the first scanner, sothat an image transfer optical system is formed between the aperture andan object arranged behind the lens.

Still furthermore, a numerical aperture calculated by the mirrordiameter of the second scanner and the distance between the lens and theobject is set to be not less than 0.08.

In this manner, the number of beam irradiation on an object can beincreased, the productivity can be improved and the productivity can beachieved similarly even in precise hole drilling.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a laser machining device according toEmbodiment 1 of the present invention.

FIG. 2 is a diagram for explaining laser irradiation positions accordingto Embodiment 1 of the present invention.

FIG. 3 is a diagram showing the configuration of an optical systemaccording to Embodiment 1 of the present invention.

FIG. 4 is a schematic diagram of a laser machining device according toEmbodiment 2 of the present invention.

FIG. 5 is a diagram for explaining laser irradiation positions accordingto Embodiment 2 of the present invention.

FIG. 6 is a schematic diagram of a laser machining device according toEmbodiment 3 of the present invention.

FIG. 7 is a diagram showing the configuration of an optical systemaccording to Embodiment 3 of the present invention.

FIG. 8 is a schematic diagram of a laser machining device according toEmbodiment 4 of the present invention.

FIG. 9 is a diagram showing a conventional laser machining device.

FIG. 10 is a diagram showing the configuration of a conventional opticalsystem.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1.

FIG. 1 shows a laser machining device according to the embodiment. InFIG. 1, a laser machining device 1 has: a laser oscillator 3 forgenerating a laser beam 2; a bend mirror 4 arranged to guide the laserbeam 2 emitted from the laser oscillator 3 in a desired direction byreflection; sub-deflecting galvanometer scanners (first galvanometerscanners) 6 having sub-deflecting galvanometer mirrors (firstgalvanometer mirrors) 5 which are sequentially arranged along an opticalpath and can be moved to deflect the laser beam 2; galvanometer scanners(second galvanometer scanners) 8 having main deflecting galvanometermirrors (second galvanometer mirrors) 7 which sequentially arrangedalong an optical path and can be moved to deflect the laser beam 2; anFθ lens 10 for converging the laser beam 2 onto an object 9; and an X-Ystage 11 having an upper surface on which the object 9 is fixed anddriven on an X-Y plane. The sub-deflecting galvanometer mirrors 5 areconstituted by two galvanometer mirrors including a galvanometer mirrorcorresponding to the X direction of the X-Y stage 11 and a galvanometermirror corresponding to the Y direction. The two sub-deflectinggalvanometer scanners are arranged to drive these mirrors. The maindeflecting galvanometer mirrors 7 are similarly constituted by twogalvanometer mirrors including a galvanometer mirror corresponding tothe X direction of the X-Y stage 11 and a galvanometer mirrorcorresponding to the Y direction. The two main deflecting galvanometerscanners are arranged to drive these mirrors.

An operation of the device according to the present invention will bedescribed below.

The laser beam 2 oscillated according to a frequency and an output valuepreset by the laser oscillator 3 and having a pulse waveform is guidedto the sub-deflecting galvanometer mirrors 5 of the sub-deflectinggalvanometer scanners 6 and the main deflecting galvanometer mirror 7 ofthe main deflecting galvanometer scanners 8 by the bend mirror 4.

In this manner, the sub-deflecting galvanometer scanners 6 and the maindeflecting galvanometer scanners 8 are driven, so that the laser beam 2can scan an arbitrary position within a limited area on the X-Y plane.The laser beam 2 is incident on the Fθ lens 10 at various angles.However, the laser beam 2 is corrected such that the laser beam 2 isincident on the Fθ lens 10 perpendicularly to the X-Y stage 11 by theoptical characteristics of the Fθ lens 10.

FIG. 2 is a diagram for explaining a galvanometer scan area on theobject 9 according to the embodiment.

In FIG. 2, in a scan area 12 which is an area which can be scanned bythe main deflecting galvanometer scanners 8 serving as a main deflectingmeans for deflecting the laser beam 2 at a large angle, sub-scan areas13 which can be scanned by the sub-deflecting galvanometer scanners 6serving as sub-deflecting means for deflecting the laser beam 2 at asmall angle are arranged.

These relations will be described below with reference to concreteexamples. It is assumed that the scan area 12 is a regular square areawhich has one side having a length of 50 mm. In this case, when thesub-scan area 13 is set to be a regular square area which has one sidehaving a length of 5 mm, up to 100 scan areas 12 can be arranged in themain deflecting scan area.

An operation of the sub-deflecting galvanometer scanners 6 and the maindeflecting galvanometer scanners 8 corresponding to the divided scanareas as described above will be described below.

When the sub-deflecting galvanometer scanners 6 and the main deflectinggalvanometer scanners 8 do not receive commands from control devices(not shown), the sub-deflecting galvanometer scanners 6 and the maindeflecting galvanometer scanners 8 are held at specific referencepositions. The reference positions can be changed by adjustment of anoptical path and a setting on the control. However, in this case,positions where the laser beam 2 is irradiated on the center of the scanarea 12 in the state that the laser beam 2 passes through deflectioncenters of the respective galvanometer mirrors are set as referencepositions.

The irradiation position of the laser beam 2 moves to a preset position14 serving as the center of a sub-scan area 13 such that the maindeflecting galvanometer scanners 8 are driven from the referencepositions in the scan area 12. The main deflecting galvanometer scanners8 are held at the positions, and the sub-deflecting galvanometerscanners 6 are driven, so that machining is performed in a sub-scan area13. In this manner, upon completion of the machining in one of thesub-scan areas 13, the main deflecting galvanometer scanners 8 aredriven to move the irradiation position of the laser beam 2 to thecenter position of the next sub-scan area, so that machining isperformed. The operation is repeated until machining is completed in theentire area of one scan area 12. When the machining is completed, theX-Y stage 11 is driven, and machining for the next scan area isperformed. The operation is repeated until machining for an entireexpected area set on the object 9 is completed.

FIG. 3 is a schematic diagram showing the positional relationships ofeach optical components of the embodiment. In FIG. 3, a flux of lightindicated by solid lines expresses the laser beam 2 reaching the object9 through an aperture 15 formed in a laser output unit of the laseroscillator 3 or in the middle of an optical path in front of the laseroutput unit, a center position 16 in an optical axis direction betweenthe two galvanometer mirrors of the sub-deflecting galvanometer mirrors5, a center position 17 in an optical axis direction between the twogalvanometer mirrors of the main deflecting galvanometer mirrors 7, andthe Fθ lens 10. At this time, the respective galvanometer mirrors areheld at the reference positions. On the other hand, a flux of lightindicated by dotted lines is the laser beam 2 which is deflected suchthat the sub-deflecting galvanometer mirror 5 is changed from thereference position. As shown in the figure, it must be considered thatthe laser beam 2 is deflected (offset) by the sub-deflectinggalvanometer mirrors 6 and partially gets out of the main deflectinggalvanometer mirrors.

For this reason, when a precise hole having a diameter of about 100 μmor less is machined, as expressed by equation (1), in addition to thedistance between the Fθ lens 10 and the object 9 and the effectivediameters of the main polarizing galvanometer mirrors 7, the positionalrelationships between the main deflecting galvanometer mirrors 7 and thesub-deflecting galvanometer mirrors 5, and the deflecting angles of thesub-deflecting galvanometer mirrors 5 are considered so that the laserbeam is prevented from getting out of the main deflecting galvanometermirrors 7. A numerical aperture NA must be held to satisfy NA>0.08.

In this manner, when the sub-deflecting galvanometer mirrors 5 are movedby a small angle, high-speed positioning can be performed within arelatively small sub-scan area, and a machining time can be shortened.Since the main deflecting galvanometer scanners are used in movementbetween sub-scan areas, the speed of movement is higher than that ofmovement by the X-Y stage, and a moving time is shortened.

In the embodiment, the galvanometer scanners which drives thegalvanometer mirrors are used as means for sub-deflecting a laser beam.However, a scanner which deflects a laser beam by applying a current toan element by using a piezoelectric element such as a piezo or a scannerconstituted by an acoustic optical element which changes a deflectionangle of a laser beam depending on an ultrasonic frequency may be used.

Embodiment 2.

FIG. 4 is a schematic diagram of a laser machining device according toEmbodiment 2 of the present invention. The same reference numerals as inEmbodiment 1 denote components of the same names in the embodiment.

In FIG. 4, a laser machining device 1 has: an aperture 15 for settingthe beam spot diameter of a linearly polarized laser beam 18 emittedfrom a laser oscillator 3 (not shown) to an arbitrary beam spot diameteron an object 9; a splitting means 19 for splitting the laser beam 18passing through the aperture 15 into a second laser beam (to be referredto as a laser beam 18 a hereinafter) and a first laser beam (to bereferred to as a laser beam 18 b hereinafter); a phase plate 20 forturning a polarization direction of the laser beam 18 a at 90°;galvanometer scanners 6 having sub-deflecting galvanometer mirrors 5which are sequentially arranged along an optical path and can be movedto deflect the laser beam 18 b at a small angle; a polarized beamsplitter 21 for reflecting the laser beam 18 a (S-polarized beam) turnedat 90° by the phase plate 20 and transmitting the laser beam 18 b(P-polarized beam) from the sub-deflecting galvanometer mirrors 5; amain deflecting galvanometer scanner 8 having a main deflectinggalvanometer mirror 7 for deflecting the laser beams 18 a and 18 b fromthe polarized beam splitter 21 at a large angle; an Fθ lens 10 forconverging the laser beams 18 a and 18 b onto the object 9; and an X-Ystage 11 (not shown) having an upper surface on which the object 9 isfixed and driven on an X-Y plane. The two sub-deflecting galvanometerscanners 6 can guide the laser beam 18 b out of the polarized beamsplitter 21. For this reason, a beam absorber 22 for receiving andabsorbing the laser beam 18 b in such a case is arranged.

In order to change the directions of the optical paths of the laserbeams 18 a and 18 b, a bend mirror 4 is used. Although not shown in FIG.4, in order to make it possible to irradiate a laser beam on anyposition on the X-Y plane as in Embodiment 1, the sub-deflectinggalvanometer mirrors 5, the sub-deflecting galvanometer scanners 6, themain deflecting galvanometer mirror 7, and the main deflectinggalvanometer scanner 8 are constituted by mirrors and scanners which aredriven in the X direction and mirrors and scanners which are driven inthe Y direction.

An operation in Embodiment 2 of the present invention will be describedbelow.

The laser beam 18 which is a linearly polarized beam is split into thelaser beams 18 a and 18 b having a strength ratio of 1:1 by thesplitting means 19. The polarization direction of the laser beam 18 a isturned at 90° by the phase plate 20 to obtain an S-polarized beam. Asthe splitting means 19, a diffractive optics is suitable because thesplitting means 19 can stabilize a spectral ratio regardless of a stainor the like of the element. As the phase plate 20, a λ/2 plate or thecorresponding component is used.

In this manner, the laser beam 18 a which is the S-polarized beam isreflected by the polarized beam splitter 21, and an irradiation positionon the object 9 is determined by the main deflecting galvanometerscanner 8. On the other hand, the laser beam 18 b split by the splittingmeans 19 is incident on the sub-deflecting galvanometer scanners 6 as aP-polarized beam, and is incident on a position different from theposition of the laser beam 18 a on the main deflecting galvanometerscanner 8. Therefore, a relative irradiation position of the laser beam18 b on the object 9 corresponding to the irradiation position of thelaser beam 18 a on the object 9 is determined by the sub-deflectinggalvanometer scanner 6.

FIG. 5 is a schematic diagram of laser irradiation positions whenirradiation is performed onto the object by the laser machining deviceaccording to this embodiment.

In FIG. 5, in a scan area 12 obtained by the main deflectinggalvanometer scanner 8 on the object 9, when irradiation of the laserbeam 18 from the laser oscillator 3 (not shown) is performed once, bypositioning performed by the main deflecting galvanometer scanner 8, thelaser beams 18 a and 18 b are simultaneously irradiated on a beamirradiation position 23 obtained by the laser beam 18 a and a beamirradiation position 24 obtained by the laser beam 18 b.

As in a case in which an odd-number of holes are to be machined in thescan area 12 on the object 9, it is not always good that the laser beamsare irradiated on two positions. In this case, only the laser beam 18 ais irradiated on a desired position 25 by the main deflectinggalvanometer scanner 8, and the laser beam 18 b is absorbed by the beamabsorber 22 under the control of the sub-deflecting galvanometerscanners 6, so that the laser beam 18 b is prevented from being incidenton the main deflecting galvanometer scanner 8.

The positional relationships of the respective optical componentsaccording to this embodiment can be expressed like FIG. 3. Morespecifically, the dotted lines in FIG. 3 correspond to a flux of lightof the laser beam 18 b deflected by the sub-deflecting galvanometerscanners 6. Therefore, a thinking which holds a numerical aperture NA tosatisfy NA>0.08 is the same as that in Embodiment 1.

With the above configuration, laser beams can be simultaneouslyirradiated on two points, a machining time can be shortened.

Only one Fθ lens may be used, the cost can be prevented from beingincreased, and a machining machine can be prevented from being increasedin size.

Embodiment 3.

FIG. 6 is a schematic diagram of a laser machining device according toEmbodiment 3 of the present invention. The same reference numerals as inEmbodiment 1 denote components of the same names in this embodiment.

In FIG. 6, a laser machining device 1 has: an aperture 15 for settingthe beam spot diameter of a laser beam 26 emitted from a laseroscillator 3 (not shown) to an arbitrary beam spot diameter on an object9; a splitting means 19 for splitting the laser beam 26 passing throughthe aperture 15 into a laser beam 26 a and a laser beam 26 b;galvanometer scanners 5 b having first sub-deflecting galvanometermirrors 5 a which are sequentially arranged along an optical path andcan be moved to deflect the laser beam 26 b at a small angle;galvanometer scanners 6 b having second sub-deflecting galvanometermirrors 6 a which are arranged along an optical path after thegalvanometer scanners 6 a and can be moved to deflect the laser beam 26b at a small angle; a main deflecting galvanometer scanner 8 having amain deflecting galvanometer mirror 7 for deflecting the laser beams 26a and 26 b at a large angle; an Fθ lens 10 for converging the laserbeams 26 a and 26 b onto the object 9; and an X-Y stage 11 (not shown)having an upper surface on which the object 9 is fixed and driven on anX-Y plane. The first sub-deflecting galvanometer scanners 5 b can guidethe laser beam 26 b besides the second sub-deflecting galvanometermirrors 6 a. For this reason, a beam absorber 22 for receiving andabsorbing the laser beam 26 b in such a case is arranged.

In order to change the directions of the optical paths of the laserbeams 26 a and 26 b, a bend mirror 4 is used. Although not shown in FIG.6, in order to make it possible to irradiate a laser beam on anyposition on the X-Y plane as in Embodiment 1, the first sub-deflectinggalvanometer mirrors 5 a, the first sub-deflecting galvanometer mirrors5 b, the second sub-deflecting galvanometer scanners 6 a, the secondgalvanometer scanners 6 b, the main deflecting galvanometer mirror 7,and the main deflecting galvanometer scanner 8 are constituted bymirrors and scanners which are driven in the X direction and mirrors andscanners which are driven in the Y direction.

In this manner, a first sub-deflecting galvanometer scanner 5 b and thesecond sub-deflecting galvanometer scanner 6 b are arranged, so that thesplit laser beams 26 a and 26 b pass through the main deflectinggalvanometer scanners 8 at the front focal point of the Fθ lens 10 on anFθ lens axis.

An operation of Embodiment 3 of the present invention will be describedbelow.

The laser beam 26 is split into the laser beams 26 a and 26 b having astrength ratio of 1:1 by the splitting means 19. As the splitting means19, a diffractive optics is suitable because the splitting means 19 canstabilize a spectral ratio regardless of a stain or the like of theelement.

In this manner, the laser beam 26 a is incident on the main deflectinggalvanometer scanner 8, so that irradiation positions onto the object 9are determined. On the other hand, the laser beam 26 b split by thesplitting means 19 is incident on the first sub-deflecting galvanometerscanner 5 b, is incident on the second sub-deflecting galvanometerscanner 6 b, and is incident on a position different from the positionof the laser beam 26 a on the main deflecting galvanometer scanner 8.Therefore, a relative irradiation position of the laser beam 26 b on theobject 9 corresponding to the irradiation position of the laser beam 26a on the object 9 is determined by the first sub-deflecting galvanometerscanner 5 b and the second sub-deflecting galvanometer scanner 6 b.

The relationships of the first sub-deflecting galvanometer mirror 5 a,the second sub-deflecting galvanometer mirror 6 a, and the maindeflecting galvanometer mirror 7 are set as described below. That is,the first sub-deflecting galvanometer mirror 5 a is inclined at an anglecorresponding to an irradiation position of the laser beam 26 a, and thesecond sub-deflecting galvanometer mirror 6 a returns the laser beam 26b such that the laser beam 26 b passes through a position correspondingto a front focus position of the Fθ lens 10 on the center axis of the Fθlens 10. In this manner, the laser beam 26 b passes through an effectivearea of the main deflecting galvanometer mirror 7 arranged at a positioncorresponding to the front focus position of the Fθ lens 10 on thecenter axis of the Fθ lens 10.

FIG. 7 is a schematic diagram showing the positional relationships ofrespective optical components according to this embodiment. In FIG. 7, aflux of light indicated by solid lines expresses the laser beam 26 areaching the object 9 through an aperture 15, a central position in anoptical axis direction between the two main deflecting galvanometermirrors constituting the main deflecting galvanometer mirror 7, and theFθ lens 10. On the other hand, the laser beam 26 b is irradiated on themain deflecting galvanometer mirror 7 without being offset because thelaser beam 26 b passes through the front focus position of the Fθ lens10 on the center axis of the Fθ lens 10. This is equivalent to that theposition of the aperture 15 moves at an angle of 90 with respect to theoptical axis direction like a flux of light indicated by dotted lines inFIG. 7.

Since the optical system is constituted as described above, in thedevice according to this embodiment, when an effective diameter of themain deflecting galvanometer mirror is determined, it need not beconsidered that the laser beam is swung by a sub-deflecting galvanometerscanner. An area in which beams can be simultaneously irradiated by thesub-deflecting galvanometer scanner and the main deflecting galvanometerscanner is widened without holding the small diameter, and a machiningspeed increases. However, in order to perform precise hole drilling, anelement (e.g., a distance between the Fθ lens and the object) except forthe effective diameter of the galvanometer mirror must be considered tosatisfy the numerical aperture>0.08.

When irradiation is performed to the object by the device according tothis embodiment, as in the case shown in FIG. 5 in Embodiment 2, thelaser beam 26 a and the laser beam 26 b are simultaneously irradiated ontwo positions. When a laser beam is irradiated on one position, thefirst sub-deflecting galvanometer scanner 5 b causes the laser beam 26 bto be absorbed by the beam absorber 22.

In Embodiment 2 and Embodiment 3, although each of the sub-deflectinggalvanometer scanners uses two galvanometer mirrors, the sub-deflectinggalvanometer scanner may use only one galvanometer mirror. In this case,although scanning in only one direction on the X-Y plane on the object 9is performed, the scanning is effective depending on the arrangement ahole to be machined, and the device configuration is simplified byreducing the number of galvanometer mirrors.

The above embodiment describes the case in which the laser machiningdevice is applied to precise hole drilling. However, the laser machiningdevice can also be applied to another laser machining as a matter ofcourse.

Embodiment 4.

FIG. 8 is a schematic diagram of a laser machining device according toEmbodiment 4 of the present invention. The same reference numerals as inEmbodiment 1 and Embodiment 2 denote the same parts in Embodiment 3.

FIG. 8, a laser machining device 1 has: an aperture 15 for setting thebeam spot diameter of a circularly polarized laser beam 27 emitted froma laser oscillator 3 (not shown) to an arbitrary beam spot diameter onan object 9; a spectral polarizing beam splitter 28 for splitting thelaser beam 27 passing through the aperture 15 into a laser beam 27 a anda laser beam 27 b; a bend mirror 4 which is combined such that the laserbeam 27 a serving as a P-polarized beam for the spectral polarizing beamsplitter 28 serves as an S-polarized beam for a coupling polarizing beamsplitter 29; sub-deflecting galvanometer scanners 6 a havingsub-deflecting galvanometer mirrors 5 which are sequentially arrangedalong an optical path and can be moved to deflect the laser beam 27 bsplit by the spectral polarizing beam splitter 28 at a small angle; acoupling polarizing beam splitter 29 for coupling the laser beam 27 aserving as an S-polarized beam and the laser beam 27 b from thesub-deflecting galvanometer mirrors 5; a main deflecting galvanometerscanner 8 having a main deflecting galvanometer mirror 7 for deflectingthe laser beams 27 a and 27 b from the coupling polarizing beam splitter29 at a large angle; an Fθ lens 10 for converging the laser beams 27 aand 27 b onto the object 9; and an X-Y stage 11 (not shown) having anupper surface on which the object 9 is fixed and driven on an X-Y plane.The sub-deflecting galvanometer scanners 6 can guide the laser beam 27 bout of the coupling polarizing beam splitter 29. For this reason, a beamabsorber 22 for receiving and absorbing the laser beam 27 b in such acase is arranged.

The bend mirror 4 is also used when the direction of the optical path ofthe laser beam 27 b is changed. Although not shown in FIG. 8, in orderto make it possible to irradiate a laser beam on any position on the X-Yplane as in Embodiment 1, the sub-deflecting galvanometer mirrors 5, thesub-deflecting galvanometer scanners 6, the main deflecting galvanometermirror 7, and the main deflecting galvanometer scanner 8 are constitutedby mirrors and scanners which are driven in the X direction and mirrorsand scanners which are driven in the Y direction.

An operation of Embodiment 4 according to the present invention will bedescribed below.

The laser beam 27 serving as a circularly polarized beam is split intothe laser beams 27 a and 27 b having a strength ratio of 1:1 by thespectral polarizing beam splitter 28, and the polarizing direction ofthe laser beam 27 a is changed by the bend mirror 4 to be an S-polarizedbeam for the coupling polarizing beam splitter 29.

In this manner, the laser beam 27 a serving as the S-polarized beam forthe coupling polarizing beam splitter 29 is incident from the couplingpolarizing beam splitter 29 on the main deflecting galvanometer scanner8, so that irradiation positions onto the object 9 are determined. Onthe other hand, the laser beam 27 b split by the spectral polarizingbeam splitter 28 is incident on the sub-deflecting galvanometer scanner6, and is incident on a position different from the position of thelaser beam 27 a from the coupling polarizing beam splitter 29 to themain deflecting galvanometer scanner 8. Therefore, a relativeirradiation position of the laser beam 27 b on the object 9corresponding to the irradiation position of the laser beam 27 a on theobject 9 is determined by the sub-deflecting galvanometer scanners 6.

The relationships of the respective optical components of thisembodiment are the same as the relationships shown in FIG. 3. Morespecifically, the dotted lines in FIG. 3 correspond to a flux of lightof the laser beam 27 b deflected by the sub-deflecting galvanometerscanners 6.

In each of the laser machining devices described in Embodiments 2 to 4,when the distances of optical paths in which the split first and secondlaser beams are propagated are equal to each other, holes having equaldiameters can be machined on an object.

Industrial Applicability

As has been described above, a laser machining device according to thepresent invention is useful as a device which performs machining byirradiating a laser beam on an object.

1. A laser machining device comprising: a first scanner for deflecting atraveling direction of a first laser beam to an arbitrary direction witha mirror; a second scanner for deflecting traveling directions of asecond laser beam and said first laser beam passing through said firstscanner to arbitrary directions with mirrors; and a lens for convergingsaid second laser beam and said first laser beam passing through saidsecond scanner.
 2. A laser machining device according to claim 1,wherein the first laser beam and the second laser beam have differentpolarization directions, and a beam splitter which reflects one laserbeam and transmits the other laser beam is arranged in front of thesecond scanner such that the laser beams from said beam splitter arepropagated to said second scanner.
 3. A laser machining device accordingto claim 2 comprising: an oscillator; a diffractive optics for splittinga linearly polarized laser beam oscillated from said oscillator into afirst laser beam and a second laser beam; and a phase plate for changingthe polarization direction of said second laser beam.
 4. A lasermachining device according to claim 2 comprising: an oscillator; and aspectral beam sputter for splitting a circularly polarized laser beamoscillated from said oscillator into a first laser beam and a secondlaser beam having different polarization directions, respectively.
 5. Alaser machining device according to claim 3, wherein an aperture isformed in front of the diffractive optics, so that an image transferoptical system can be formed between the aperture and an object arrangedbehind the lens.
 6. A laser machining device according to claim 4,wherein an aperture is formed in front of the spectral beam splitter, sothat an image transfer optical system can be formed between the apertureand an object arranged behind the lens.
 7. A laser machining deviceaccording to claim 5, wherein a distance in which the first laser beamis propagated from the diffractive optics to the lens is made almostequal to a distance in which the second laser beam is propagated fromsaid diffractive optics to said lens.
 8. A laser machining deviceaccording to claim 6, wherein a distance in which the first laser beamis propagated from the spectral beam splitter to the lens is made almostequal to a distance in which the second laser beam is propagated fromsaid spectral beam splitter to said lens.
 9. A laser machining deviceaccording to claim 5, wherein a numerical aperture calculated by amirror diameter of the second scanner and a distance between the lensand the object is set to be not less than 0.08.
 10. A laser machiningdevice according to claim 6, wherein a numerical aperture calculated bya mirror diameter of the second scanner and a distance between the lensand the object is set to be not less than 0.08.
 11. A laser machiningdevice according to claim 7, wherein a numerical aperture calculated bya mirror diameter of the second scanner and a distance between the lensand the object is set to be not less than 0.08.
 12. A laser machiningdevice according to claim 8, wherein a numerical aperture calculated bya mirror diameter of the second scanner and a distance between the lensand the object is set to be not less than 0.08.
 13. A laser machiningdevice comprising: a first scanner for deflecting a traveling directionof a first laser beam to an arbitrary direction with a mirror; a secondscanner for deflecting traveling directions of a second laser beam andsaid first laser beam passing through at least said first scanner toarbitrary directions with a mirror; and a third scanner for deflecting atraveling direction of said first laser beam passing through said firstscanner to an arbitrary direction with a mirror; and a lens forconverging said second laser beam passing through said second scannerand said first laser beam passing through said first, second and thirdscanners.
 14. A laser machining device according to claim 13, wherein anaperture is formed on at least one of the traveling directions of thefirst laser beam in front of the first scanner, and the travelingdirection of the second laser beam in front of the second scanner sothat an image transfer optical system is formed between the aperture andan object arranged behind the lens.
 15. A laser machining deviceaccording to claim 14, wherein a numerical aperture calculated by amirror diameter of the second scanner and a distance between the lensand the object is set to be not less than 0.08.
 16. A laser machiningdevice comprising: a first scanner for deflecting a traveling directionof a laser beam to an arbitrary direction with a mirror; a secondscanner for deflecting a traveling direction of said laser beam passingthrough said first scanner to an arbitrary direction with a mirror; anda lens for converging said laser beam passing through said secondscanner, wherein an angle at which said laser beam is deflected by saidfirst scanner being smaller than an angle at which said laser beam isdeflected by said second scanner.
 17. A laser machining device accordingto claim 16, wherein an aperture is formed in front of the firstscanner, so that an image transfer optical system is formed between theaperture and an object arranged behind the lens.
 18. A laser machiningdevice according to claim 17, wherein a numerical aperture calculated bya mirror diameter of the second scanner and a distance between the lensand the object is set to be not less than 0.08.